#include <stdio.h>
#include <math.h>
double cal_e(int n){
double sum=1.0, term = 1.0;
int i;
for (i=1; i<=n; i++){
term = term * 1.0 / i; //计算当前项的值
sum += term; //将当前项加到总和中
if (fabs(term) < 1e-16) break; //如果当前项的绝对值已经小于 1e-16，则退出循环
}
return sum;
}
int main(){
int n;
double sum;
if (scanf("%d", &n) != EOF){
sum = cal_e(n);
printf("%.8f", sum);
} else {
printf("input n wrong");
}
return 0;
}
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